This invention relates generally to the field of stator vane assemblies in gas turbine or turbojet engines, and more particularly to an improved mounting assembly for impingement cooling plates.
In conventional gas turbine engines, gases, generally atmospheric air, are compressed in a compression section of the engine and then flowed to a combustion section where fuel is added and the mixture burned to add energy to the flowing gases. The now high energy combustion gases are then flowed to a turbine section where a portion of the energy is extracted and applied to drive the engine compressor.
The turbine section includes a number of alternate rows of fixed stator vanes and moveable rotor blades. Each row of stator vanes directs the combustion gases to a preferred angle of entry into the downstream row of rotor blades. The rotor blades in turn extract energy from the combustion gases for driving the engine compressor.
The combustion gases are very hot, creating a need for cooling of the stator vanes and turbine blades. Part of the cooling requirements for the stator vanes is provided by passing cooling air over the base of the platform to which each stator vane is attached. For more efficient cooling, an impingement cooling plate is placed between the base of each platform and the cooling air source. The impingement cooling plates are perforated so that the cooling air is redirected to form jets of air impacting perpendicularly to the platform bases. This increases the cooling over what would result if the cooling air merely passed over the base of each platform. Other designs align the perforation holes to direct the jets of cooling air in other advantageous directions; for example, to direct cooling air to particular hot spots.
Prior art impingement cooling plates are typically welded to the platform bases at the plate edges. These welds add a manufacturing expense and create a thermal fight between the plate and the platform when the turbine is operated. The thermal fight can cause weld cracks. The welds also make repairs more difficult.
With the foregoing in mind, it is, therefore, a principal object of the present invention to provide an impingement cooling plate mounting assembly with a lower manufacturing cost, easier repairability and increased reliability over welded-in-place impingement cooling plates.